Percussion drill



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L. G. LANDSTEDT 2,956,783 PERCUSSION DRILL I v 3 Shets-Shet 3 v v Filed Oct. 10. 1957 INVENTOR. I

Arrows vs,

United States Patent F PERCUSSION DRILL Lars Giihte Landstedt, Sandviken, Sweden,

Sandvikens Jernverks Aktiebolag, a corporation of Sweden assignor to Sandviken, Sweden,

The present invention relates to percussion drills and more particularly to drills which are used for earth boring or boring in rock which may be covered with loose layers of earth.

The drill constructions which have been developed prior to the present invention have the disadvantage that after the drilling has been in progress for some time they often stick in the drill hole because the hole tends to fill in with dirt behind the drill head. Moreover, in constructions wherein a plurality of drill rods are coupled longitudinally in end-to-end relation, it has often proved diificult to remove the drill from the drill hole due to the sticking action.

Various solutions have been proposed to overcome the tendency of the drill to stick. For example, it has been proposed to surround the drill rod, or coupled drill rods with a covering tube. However, with prior proposed constructions it has proven diflicult to maintain the protecting tube in the correct position during the drilling operation in order to prevent dirt and other similar material from getting into the tube.

A principal object of the present invention is to provide an improved arrangement for a protective tube surrounding the drill rod, the organization being such that the lower end of the tube adjacent the drill bit is not only maintained in the proper centralized position on the drill bit but is also restrained against longitudinal movement thus preventing entry of any dirt or other foreign matter into the tube between the lower end thereof and the drill bit.

More particularly, the upper end of the protective or covering tube remote from the drill bit is surrounded by and effectively secured to a sleeve. The outer surface of the sleeve is provided with a plurality of flanges or threads or the like which are adapted to engage complementary flanges or threads on a connecting coupling or locking device which is arranged on the drill rod in such manner as to prevent longitudinal movement along the rod. Consequently, through the coupling device and sleeve with which it is engaged, the covering tube is likewise held against longitudinal displacement with respect to the drill rod and bit and also centered about the same. Preferably, the coupling device is divided into two or more separable symmetrical sections which are held in their proper positions within an outer sleeve or muff which can be slid longitudinally so as to free the sections of the coupling device and enable them to be removed from the sleeve which surrounds the end of the covering tube thus freeing the latter for longitudinal movement in a direction away from the drill bit.

One practical embodiment of the invention is disclosed in the following detailed description and in the accompanying drawings wherein Fig. 1 is a view in central horizontal longitudinal section of the upper portion of the drill rod showing the upper end of the covering tube, the sleeve surrounding the same, and the coupling device engaged with the sleeve for centering the sleeve and covering tube with respect to the axis of the drill rod and for 2,956,783 Patented Oct. 18, 1960 preventing longitudinal movement of the covering tube, and Fig. 2 is likewise a view partly in central longitudinal section and partly in elevation showing the lower end of the drill rod and bit and covering tube in proper position to exclude dirt and other foreign matter from the interior thereof, and Fig. 3 is a transverse sectional view taken along line 33 of Fig. 1, showing the two-part form of the locking device.

With reference now to Fig. 2, the drill bit indicated generally by numeral 11 is seen to be provided with a threaded pin portion 12 at the upper end thereof which is threaded into an internally threaded portion of a coupling sleeve 10, the latter being similarly threadedly connected to a drill rod 17 shown in Fig. l. Surrounding an intermediate portion of the drill bit is a frontal sleeve 14 which at its front end engages a tapered portion 13 of the drill bit. The rear end of sleeve 14 has a portion 15 of reduced diameter corresponding to the inner diameter of the covering tube 16, the lower end of the latter being telescoped over the reduced portion 15. The outer diameter of the covering tube 16 is preferably made slightly smaller than the point of greatest diameter or Width of the drill bit which in the present case is represented by the outer ends of the cutting inserts 11' at the lower end of the bit. If desired, the frontal sleeve 14 may be so constructed as to make threaded engagement with the lower end of the covering tube 16, for example when it is desired to have the drill continue its penetration in rock after having drilled through an earth layer.

In order to maintain the lower end of the covering tube 16 and the frontal sleeve 14 pressed against the tapered surface 13 of the drill bit, it will be seen from Fig. 1 that the upper end of the covering tube 16 is surrounded by a sleeve 19. Sleeve 19 is provided with an internal shoulder 19a bearing against the end face of the covering tube 16. Thus any longitudinal force exerted on sleeve 19 in the direction of the drill bit will force the covering tube 16 in the same direction. The sleeve 19 can fit somewhat snugly about the tube or it can be threaded or shrunk onto the same so that longitudinal forces applied to sleeve 19 will be transmitted to tube 16. The outer surface of sleeve 19 is provided with a plurality of outwardly facing flanges 20 adapted to be interlocked with complementary configured inwardly facing flanges 21 on a coupling device 22 (conststing of two parts 22a, 22b as shown in Fig. 3 arranged around the drill rod 17 and end sleeve 19. The upper end faces of the coupling device 22 bear against the end face of some suitable fixed collar portion surrounding the drill rod such as, for example, the coupling sleeve 23 which threads through these interengaged parts, the covering tube 16 is maintained against longitudinal displacement and hence the lower end thereof and the frontal sleeve 14 are maintained against the tapered surface 13 of the drill bit in the position indicated in Fig. 2 so as to exclude dirt and other matter from the interior of the tube 16. In certain applications, the flanges 20 may be replaced with external threads of the same pitch, or different portions of the sleeve 19 may be provided with threads of opposite pitch, such threads being engaged with complementary internal threads on the locking device 22 in order to enable the latter to be turned and moved longitudinally in the direction of a collar portion on the drill rod such as the end face of coupling sleeve 23 and thus prevent any longitudinal displacement of the covering tube 16 in the direction away from the drill bit.

The two-part coupling device 22 may be maintained in assembled relation to the sleeve 19 by means of an ouer sleeve or muff 24 closely surrounding the coupling device 22 and which is slidable longitudinally of the drill rod 17. When the muff 24 is slid into position over the outer edges of the coupling device 22, the latter is maintained in assembled position thus coupling the sleeve 19 and covering tube 16 against displacement. By sliding the muff 24 off the coupling device i.e. to the left from the position shown in Fig. 1, the latter is then free to be removed thus releasing the sleeve 19 and covering tube 16 for longitudinal movement. The muff 24 is maintained in its position shown in Fig. l by gravity but it is obvious that it may be secured in such position by any suitable positive securing means.

It is possible to use the improved drill arrangement for drilling in rock, after passing through an earth layer. Upon passing the earth layer, the coupling device 22 can then be released and the covering tube 16 kept steady in the drill holeas the drill feed proceeds. Especially for rock drilling it may be suitable in or near the drill rod to arrange recesses or the like for passage of drilled material, drill powder and flushing medium, the latter being fed to the drill bit in a Well known manner. When changing from earth to rock drilling it may be preferred to allow the end sleeve 19 to stay at the rear end of the covering tube 16.

A drilling operation carried out with a construction according to the present invention makes it easy to longitudinally couple additional covering tubes and drill rods without any appreciable loss in time. As the lengths of both drill rods and covering tubes vary within tolerance limits, the distance between the coupling sleeve 23 for the drill rods 17 and covering tube 16 may be changed at each new coupling. One advantage of the improved construction according to the invention is that the coupling device 22 and end sleeve 19, being adjustable longitudinally; is usable also if the aforementioned distance varies within wide It may therefore preferably be used also for the drilling of long holes.

In conclusion it is to be understood that the embodiment of the invention as specifically described and illustrated can be departed from in various respects without, however, departing from the spirit and scope of the inventive concept as defined in the appended claim.

I claim:

A percussion drill comprising a drill rod having a drill bit secured to the lower end thereof, a covering tube coaxially arranged about and spaced from said drill rod, the lower end of said covering tube terminating adjacent said drill bit, a sleeve member coaxially mounted upon the upper end of said covering tube, said sleeve member having shoulder means cooperating with the upper extremity of said covering tube for preventing longitudinal movement of said sleeve member relative to said tube in the direction of said tool bit, a tubular coupling device removably mounted coaxially about said sleeve member, said coupling device having at least one radial flange on the inner periphery thereof in removable engagement with longitudinally spaced radial flanges on the outer periphery of said sleeve member, said coupling device being longitudinally divided into at least two parts, and an outer tubular muff coaxially mounted upon said coupling device to maintain said longitudinally divided parts thereof in engagement with said sleeve flanges, said coupling device being abuttedly connected to said drill rod to prevent movement of said coupling device relative to said drill rod in the longitudinal direction away from said drill bit.

'Diokenson July 23, 1912 Joy July 29, 1941 

